Many devices use power amplifiers to amplify a signal and provide it as output from the device. Typically, the power amplifier accepts power from a VCC source to perform amplification. The power output from the amplifier is generally proportional to the square of the VCC power (VCC2). If the VCC power source is regulated the power output will be stable. However if the VCC power source is not regulated then the power output may fluctuate. A small change in the value of the VCC power source will lead to a large change in the power of the output signal, since it is proportional to the square of the power source.
In miniature devices and battery powered devices the addition of elements to regulate the power source is generally less feasible. In such devices the power output may fluctuate and may reach high values that can damage circuit elements (e.g. transistors or integrated circuits) or reduce their lifespan. Additionally, a high power output exceeding the original design may interfere with the functionality of other devices in the vicinity of the device and may cause the device to function against regulations (e.g. FCC standards). Likewise a low power output due to fluctuations may not provide enough power to enable recipients to receive the transmitted signal although they are in a pre-designated range from the transmitter.
There is thus a need to stabilize the power output of a power amplifier especially when the power source is unregulated. Standard solutions include additional elements coupled to the output of the power amplifier, for example an RF coupler or an RF power detector. The coupler or detector monitor the power output and provide feedback to the device to instruct it to reduce or increase the power provided to the power amplifier. However such solutions require additional elements external to the amplifying circuitry of the device and increase the cost of the device. It would be desirable to stabilize the power output of a device without a regulated power source by controlling the power consumption of the power amplifier from within the device.